I am running a Mac Pro Quad Core Xeon with 8 internal cores. 2.93 Ghz and 6 Gig of RAM using a ATI 4870 video card. Running Windows 7 Professional. It runs off of a 1 Tb Sansung HD103UJ SATA 3 so this system is no where near the lower middle recommended.
Since 1.1 patch fans run almost full blast on video card and computer. The Mac Pro has 7 fans so it gets real noisy fast.
What ever they did in this patch is BROKEN the only other time my computer ever did this was a CRAPPY PATCH done by Blizzard in WoW.
This Patch is a mess and 100% of the problem we have.
The game is even worse for crashing and locking up. Please examine your code for errors.
Try this, I found this out the other day. Even though I have v-sync turned ON in the preferences, it was OFF. I clicked the button off, hit apply, clicked the button on, hit apply and my FPS went to 60fps like it should (it was 110fps before) and my video card temps went down 10*C and the fans slowed back down to where they normally are.
As for CPU usage, i5 2500k, 2 cores running around 40% usage and memory, well with 16gb of ram, with the game, vent and just a browser window I'm using 25% and never moves showing no memory leaks on my end at all.